# Draft California 2012 Integrated Report( 303(d) List/305(b) Report)

# Supporting Information

## Regional Board 6 - Lahontan Region

Water Body Name: | West Walker River
Water Body ID: | CAR6311006019980805123547
Water Body Type: | River & Stream

DECISION ID | 30713 | Region 6
West Walker River

Pollutant: | Arsenic
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30713, Arsenic | Region 6
West Walker River
LOE ID: | 43973
Pollutant: | Arsenic
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Arsenic.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for arsenic is 33 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30714 | Region 6
West Walker River

Pollutant: | Bifenthrin
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30714, Bifenthrin | Region 6
West Walker River
LOE ID: | 43921
Pollutant: | Bifenthrin
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Bifenthrin.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin from Amweg et al. (2005) and Amweg and Weston (2007).
Guideline Reference: | Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
| Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 32250 | Region 6
West Walker River

Pollutant: | Boron
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Three of five of the samples exceed the water quality objective for COLD beneficial use. There are natural sources of boron in the watershed and no known anthropogenic sources contributing to these levels. Zero of 10 samples exceed the criteria for MUN beneficial use. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Three of five samples exceeded the objective for COLD beneficial use; Zero of 10 samples exceeded the criteria for MUN beneficial use and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. REGIONAL BOARD justification for not listing: 1) 10 samples were collected between 2002-2005. Based on an annual average, there were two of four exceedences. For this listing cycle, five samples were collected between 8/8/2007 to 12/26/2007. Based on this limited data set, there is not enough substantial justification to list this waterbody. The data is not temporally representative as it does not show seasonal fluctuations and only a few samples were compiled for annual averages. 2) Boron in the West Walker River watershed comes almost entirely from natural sources. The most significant source of boron is probably Fales Hot Springs, although groundwater data show evidence of geothermal influence in the Antelope Valley area. The Fales Hot Springs discharge into Hot Creek, a tributary of the Little Walker River.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 32250, Boron | Region 6
West Walker River
LOE ID: | 32232
Pollutant: | Boron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | The annual average of Boron for 2007 for this data set was 0.20 mg/L which exceeds the site-specific Water Quality Objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The site-specific objective for Boron in the Lahontan Basin Plan page 3-42, states that the annual average for Boron shall not exceed 0.10 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data was collected at the following station: 631WWK001 (West Walker River, at Coleville).
Temporal Representation: | Samples were collected between 8/8/2007 - 12/26/2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 32250, Boron | Region 6
West Walker River
LOE ID: | 4924
Pollutant: | Boron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 2
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled boron under the Region 6 SWAMP program between 2002 and 2005. Boron concentrations in 10 samples ranged from 12 to 151 ug/L. Boron concentrations varied with flow. The highest concentration, 151 ug/L was observed at an instantaneous discharge of 25 cubic feet per second (cfs) and the lowest concentration, 12 ug/L, was associated with a discharge of 1730 cfs. Annual averages (based on one to four samples per year) were 129, 104, 98, and 69 ug/L. The annual average objective was exceeded in the two years when the "average" was based on one or two samples..
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
| 2000. Use Attainability Analysis for Nine "Naturally Impaired" Waters of the Lahontan Region. April 2000
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The site-specific objective for boron includes an annual average of 0.10 mg/L (= 100 ug/L) and a 90th percentile value of 0.20 mg/L (= 200 ug//L). See Lahontan Basin Plan Table 3-15.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Ten quarterly samples were collected including one sample in 20002, two samples in 2003, four samples in 2004 and three samples in 2005. between 2002 and 2005.
Environmental Conditions: | Boron in the West Walker River watershed comes almost entirely from natural sources. The most significant source of boron is probably Fales Hot Springs, although groundwater data show evidence of geothermal influence in the Antelope Valley area. The Fales Hot Springs discharge into Hot Creek, a tributary of the Little Walker River. A 1956 sample from Hot Creek had a boron concentration of 3300 ug/L. There are no point source POTW discharges in the watershed. The only known anthropogenic source of boron is the aerial application of borate fire retardants to fight wildfires.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 32250, Boron | Region 6
West Walker River
LOE ID: | 7779
Pollutant: | Boron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 10
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled boron under the Region 6 SWAMP program between 2002 and 2005. Boron concentrations in 10 samples ranged from 12 to 134 ug/L. The criterion was not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California State Notification Level criterion for boron is 1000 ug/L.
Objective/Criterion Reference: | Compilation of Water Quality Goals
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Ten quarterly samples were collected between 2002 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 30715 | Region 6
West Walker River

Pollutant: | Cadmium
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30715, Cadmium | Region 6
West Walker River
LOE ID: | 44035
Pollutant: | Cadmium
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cadmium.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for cadmium is 4.98 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 31855 | Region 6
West Walker River

Pollutant: | Chlordane
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 31855, Chlordane | Region 6
West Walker River
LOE ID: | 33733
Pollutant: | Chlordane
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Zero of 1 sample collected exceeded the criteria for chlordane concentration (Sum of trans-Chlordane, cis-Chlordane, cis-Nonachlor, trans-Nonachlor, and Oxychlordane).
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | Water Quality Control Plan, Lahontan Region (2005): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. Waters shall not contain substances in concentrations that result in deposition of material that causes nuisance or that adversely affects the water for beneficial uses.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The Probable Effect Concentration for Chlordane in freshwater sediments is 17.6 ug/kg.
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data were collected at the following station 631WWK008 (West Walker River at Topaz).
Temporal Representation: | One sample was collected on 9/23/2008.
Environmental Conditions: |
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 32251 | Region 6
West Walker River

Pollutant: | Chloride
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Three of five of the samples exceed the water quality objective for COLD beneficial use, although chloride may be residual from a wildfire in 2002 and/or naturally occurring because of geothermal springs. Zero of 12 samples exceeded the criteria for MUN beneficial use. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Three of five samples exceeded the objective for COLD beneficial use; Zero of 12 samples exceeded the criteria for MUN beneficial use and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. REGIONAL BOARD justification for not listing: 1) From historical data from 2002-2005, large fluctations in chloride exist in the West Walker River. The concentrations in 12 samples ranged from 0.38 to 5.01 mg/L. The data for this listing cycle 8/8/2007-12/26/2007 with five samples collected. This data is not temporarily representative to demonstrate the fluctuations that exist with chloride in this waterbody and the limited data set can not determine if in fact there is an impairment. 2) The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 32251, Chloride | Region 6
West Walker River
LOE ID: | 32239
Pollutant: | Chloride
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | The annual average for CL for this data set was 5.45 mg/L which exceeds the Water Quality Objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The site-specific objective for Chloride in the Lahontan Basin Plan page 3-42, states that the annual average for Chloride shall not exceed 3.0 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data were collected at the following station: 631WWK001 - West Walker River, at Coleville.
Temporal Representation: | Samples were collected between 8/8/2007 and 12/26/2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 32251, Chloride | Region 6
West Walker River
LOE ID: | 4925
Pollutant: | Chloride
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 2
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled chloride under the Region 6 SWAMP program between 2002 and 2005. Chloride concentrations in 12 samples ranged from 0.38 to 5.01 mg/L. The annual average objective was exceeded in two of four years.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The site-specific objective for chloride includes an annual average of 3.0 mg/L and a 90th percentile value of 5.0 mg/L (Lahontan Basin Plan Table 3-15).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly samples were collected between 2002 and 2005. Four annual average calculations were done.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 32251, Chloride | Region 6
West Walker River
LOE ID: | 4926
Pollutant: | Chloride
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled chloride under the Region 6 SWAMP program between 2002 and 2005. Chloride concentrations in 12 samples ranged from 0.38 to 5.01 mg/L. The MCL was not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for chloride is 250 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly samples were collected between 2002 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. . The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 30716 | Region 6
West Walker River

Pollutant: | Chlorpyrifos
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30716, Chlorpyrifos | Region 6
West Walker River
LOE ID: | 43951
Pollutant: | Chlorpyrifos
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Chlorpyrifos.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for chlorpyrifos is the median lethal concentration (LC50) of 1.77 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Amweg and Weston, 2007).
Guideline Reference: | Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30717 | Region 6
West Walker River

Pollutant: | Chromium
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30717, Chromium | Region 6
West Walker River
LOE ID: | 44062
Pollutant: | Chromium
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Chromium.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for chromium is 111 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30718 | Region 6
West Walker River

Pollutant: | Copper
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30718, Copper | Region 6
West Walker River
LOE ID: | 44101
Pollutant: | Copper
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Copper.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for copper is 149 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30719 | Region 6
West Walker River

Pollutant: | Cyfluthrin
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30719, Cyfluthrin | Region 6
West Walker River
LOE ID: | 43896
Pollutant: | Cyfluthrin
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cyfluthrin, total.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for cyfluthrin is the median lethal concentration (LC50) of 1.1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.1 ug/g is the geometric mean of LC50 values for cyfluthrin from Amweg et al. (2005).
Guideline Reference: | Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30720 | Region 6
West Walker River

Pollutant: | Cyhalothrin, Lambda
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guidelines and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30720, Cyhalothrin, Lambda | Region 6
West Walker River
LOE ID: | 43926
Pollutant: | Cyhalothrin, Lambda
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cyhalothrin, lambda, total.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for lambda-cyhalothrin is the median lethal concentration (LC50) of 0.44 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.44 ug/g is the geometric mean of LC50 values for lambda-cyhalothrin from Amweg et al. (2005).
Guideline Reference: | Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30721 | Region 6
West Walker River

Pollutant: | Cypermethrin
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30721, Cypermethrin | Region 6
West Walker River
LOE ID: | 43886
Pollutant: | Cypermethrin
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cypermethrin, total.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for cypermethrin is the median lethal concentration (LC50) of 0.3 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.3 ug/g is the geometric mean of LC50 values for cypermethrin from Maund et al. (2002).
Guideline Reference: | Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30722 | Region 6
West Walker River

Pollutant: | Deltamethrin
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30722, Deltamethrin | Region 6
West Walker River
LOE ID: | 43916
Pollutant: | Deltamethrin
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Deltamethrin.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for deltamethrin is the median lethal concentration (LC50) of 0.79 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.79 ug/g is the geometric mean of LC50 values for deltamethrin from Amweg et al. (2005).
Guideline Reference: | Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30723 | Region 6
West Walker River

Pollutant: | Diazinon
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30723, Diazinon | Region 6
West Walker River
LOE ID: | 43946
Pollutant: | Diazinon
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Diazinon.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for diazinon is the median lethal concentration (LC50) of 11 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 11 ug/g is the geometric mean of LC50 values for diazinon from Ding et al. (2011).
Guideline Reference: | Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:8392.
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30724 | Region 6
West Walker River

Pollutant: | Dieldrin
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guidelines and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30724, Dieldrin | Region 6
West Walker River
LOE ID: | 43805
Pollutant: | Dieldrin
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Dieldrin.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's water quality objective for toxicity states: all waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce determental physiological responses in human, plant, animal, or aquatic life.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for dieldrin is 61.8 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 29992 | Region 6
West Walker River

Pollutant: | Dissolved oxygen saturation
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Two of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Two of 16 samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 29992, Dissolved oxygen saturation | Region 6
West Walker River
LOE ID: | 5729
Pollutant: | Dissolved oxygen saturation
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Aquatic Life Use: | Fish Spawning
Number of Samples: | 10
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured dissolved oxygen under the Region 6 SWAMP program. Ten samples collected between had percent saturation values 2002 and 2005 ranging from 92 to 117 percent. The objective was not violated.
Data Reference: | 2007. SWAMP Data for the East Fork and West Fork Carson River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's regionwide narrative objective for dissolved oxygen provides that percent saturation shall not be depressed more than 10 percent nor shall the minimum dissolved oxygen concentration be less than 80 percent of saturation.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Ten samples were collected (one sample in 2002 and 9 samples at quarterly intervals between 2003 and 2005).
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 29992, Dissolved oxygen saturation | Region 6
West Walker River
LOE ID: | 44400
Pollutant: | Dissolved oxygen saturation
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 6
Number of Exceedances: | 2
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 2 of 6 samples exceed the criterion for Oxygen, Saturation.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River, at Coleville]
Temporal Representation: | Data was collected over the time period 8/8/2007-12/26/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 30725 | Region 6
West Walker River

Pollutant: | Endrin
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30725, Endrin | Region 6
West Walker River
LOE ID: | 43815
Pollutant: | Endrin
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Endrin.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's water quality objective for toxicity states: all waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce determental physiological responses in human, plant, animal, or aquatic life.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for endrin is 207 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30726 | Region 6
West Walker River

Pollutant: | Esfenvalerate/Fenvalerate
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30726, Esfenvalerate/Fenvalerate | Region 6
West Walker River
LOE ID: | 44274
Pollutant: | Esfenvalerate/Fenvalerate
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Esfenvalerate/Fenvalerate, total.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for esfenvalerate/fenvalerate is the median lethal concentration (LC50) of 1.5 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.5 ug/g is the geometric mean of LC50 values for esfenvalerate/fenvalerate from Amweg et al. (2005).
Guideline Reference: | Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 20826 | Region 6
West Walker River

Pollutant: | Fecal Coliform
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. For 2010, a different LOE was created for both MUN and COLD beneficial uses although based on the same sample set. For the 2012 listing cycle, the same sample set was evaluated on two Basin Plan objectives. LOE ID# 34861 was not included in this data evalatued as the objective in this LOE is based on a 30-day log mean, which is not applicable for monthly sampling. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of seven samples exceeded the objective for MUN beneficial use; one of 13 samples exceeded the objective for COLD beneficial use and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 20826, Fecal Coliform | Region 6
West Walker River
LOE ID: | 5696
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 7
Number of Exceedances: | 1
Data and Information Type: | Water column surveys (e.g. fecal coliform)
Data Used to Assess Water Quality: | The U.S. Geological Survey collected quarterly samples for fecal coliform bacteria between 2003 and 2005 under the Region 6 SWAMP program. Bacteria counts in four of seven samples were estimated values. Two samples were below the detection level, and one sample was reported as greater than 240 colonies per 100 mL.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's objective for coliform bacteria states: "Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. The log mean shall ideally be based on a minimum of not less than five samples collected as evenly spaced as practicable during any 30-day period. However, a log mean concentration exceeding 20/100 ml for any 30-day period shall indicate violation of this objective even if fewer than five samples were collected."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Seven quarterly samples were collected between 2003 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. . The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20826, Fecal Coliform | Region 6
West Walker River
LOE ID: | 34861
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Assess Water Quality: | Zero of the five samples exceeded the fecal coliform objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml. Water Quality Control Plan for the Lahontan Region.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | The samples were collected from station 631WWK001 West Walker River, at Coleville.
Temporal Representation: | The samples were collected once a month from August to December 2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 20826, Fecal Coliform | Region 6
West Walker River
LOE ID: | 32255
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Assess Water Quality: | Zero of the five samples exceeded the Fecal Coliform objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The fecal coliform concentration shall not exceed more than 40/100 ml.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | The samples were collected from station 631WWK001 West Walker River, at Coleville.
Temporal Representation: | The samples were collected once a month from August to December 2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 20826, Fecal Coliform | Region 6
West Walker River
LOE ID: | 5697
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 7
Number of Exceedances: | 1
Data and Information Type: | Water column surveys (e.g. fecal coliform)
Data Used to Assess Water Quality: | The U.S. Geological Survey collected quarterly samples for fecal coliform bacteria between 2003 and 2005 under the Region 6 SWAMP program. Bacteria counts in four of seven samples were estimated values. Two samples were below the detection level, and one sample was reported as greater than 240 colonies per 100 mL.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's objective for coliform bacteria states: "Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. The log mean shall ideally be based on a minimum of not less than five samples collected as evenly spaced as practicable during any 30-day period. However, a log mean concentration exceeding 20/100 ml for any 30-day period shall indicate violation of this objective even if fewer than five samples were collected."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Seven quarterly samples were collected between 2003 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. . The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 30727 | Region 6
West Walker River

Pollutant: | Fenpropathrin
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30727, Fenpropathrin | Region 6
West Walker River
LOE ID: | 44314
Pollutant: | Fenpropathrin
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Fenpropathrin.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for fenpropathrin is the median lethal concentration (LC50) of 1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1 ug/g is the geometric mean of LC50 values for fenpropathrin from Ding et al. ( 2011).
Guideline Reference: | Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:8392.
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 31857 | Region 6
West Walker River

Pollutant: | Fluoride
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of two samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 31857, Fluoride | Region 6
West Walker River
LOE ID: | 33114
Pollutant: | Fluoride
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Zero of 2 samples exceeded the water quality objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for Fluoride is 2.0 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected at Station 631WWK001 - West Walker River, at Coleville.
Temporal Representation: | Samples were collected between 8/8/2007 and 11/8/2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 31856 | Region 6
West Walker River

Pollutant: | Iron
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of two samples exceeded the objective/guideline for both COLD and MUN beneficial uses and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 31856, Iron | Region 6
West Walker River
LOE ID: | 44304
Pollutant: | Iron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Iron.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Water Quality Control Plan for the Lahontan Region's Objective for Municipal and Domestic Supply uses of inland surface waters states that waters designated as MUN shall not contain concentrations of chemical constituents in excess of the maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL). This is based upon drinking water standards specified in the following provisions of Title 22 of the California Code of Regulations which are incorporated by reference into the Water Quality Control Plan: Table 64431-A of Section 64431 (Inorganic Chemicals), Table 64431-B of Section 64431 (Fluoride), Table 64444-A of Section 64444 (Organic Chemicals), Table 64449-A of Section 64449 (Secondary Maximum Contaminant Levels-Ranges). The maximum contaminant level listed in Table 64449-A for Iron is 0.3 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River, at Coleville]
Temporal Representation: | Data was collected over the time period 8/8/2007-11/8/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 31856, Iron | Region 6
West Walker River
LOE ID: | 44288
Pollutant: | Iron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Iron.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The Red Book states that based on field observations principally, a criterion of 1.0 mg/L iron for freshwater aquatic life is believed to be adequately protective (National Recommended Water Quality Criteria 2009).
Guideline Reference: | National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River, at Coleville]
Temporal Representation: | Data was collected over the time period 8/8/2007-11/8/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 30729 | Region 6
West Walker River

Pollutant: | Lead
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30729, Lead | Region 6
West Walker River
LOE ID: | 43835
Pollutant: | Lead
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Lead.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for lead is 128 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30730 | Region 6
West Walker River

Pollutant: | Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. [NUMBER] of [NUMBER] samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30730, Lindane/gamma Hexachlorocyclohexane (gamma-HCH) | Region 6
West Walker River
LOE ID: | 43825
Pollutant: | Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for HCH, gamma.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for Lindane (gamma-HCH) is 4.99 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30731 | Region 6
West Walker River

Pollutant: | Mercury
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30731, Mercury | Region 6
West Walker River
LOE ID: | 43845
Pollutant: | Mercury
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Mercury.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for mercury is 1.06 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30732 | Region 6
West Walker River

Pollutant: | Methyl Parathion
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. [One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30732, Methyl Parathion | Region 6
West Walker River
LOE ID: | 44354
Pollutant: | Methyl Parathion
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Parathion, Methyl.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for methyl parathion is the median lethal concentration (LC50) of 6 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 6 ug/g is the geometric mean of LC50 values for methyl parathion from Ding et al. (2011).
Guideline Reference: | Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:8392.
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30733 | Region 6
West Walker River

Pollutant: | Nickel
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30733, Nickel | Region 6
West Walker River
LOE ID: | 43855
Pollutant: | Nickel
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Nickel.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for nickel is 48.6 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 29993 | Region 6
West Walker River

Pollutant: | Nitrate/Nitrite (Nitrite + Nitrate as N)
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 17 samples exceeded the criteria and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 29993, Nitrate/Nitrite (Nitrite + Nitrate as N) | Region 6
West Walker River
LOE ID: | 7777
Pollutant: | Nitrate/Nitrite (Nitrite + Nitrate as N)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled nitrite plus nitrate under the Region 6 SWAMP program between 2002 and 2005. Two of the analytical results were estimated values and one was below the detection level. Concentrations in the remaining 9 samples ranged from 0.002 to 0.149 mg/L. The MCL was not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nitrite plus nitrate is 10 mg/L, expressed "as nitrogen."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly samples were collected between 2002 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 29993, Nitrate/Nitrite (Nitrite + Nitrate as N) | Region 6
West Walker River
LOE ID: | 44324
Pollutant: | Nitrate/Nitrite (Nitrite + Nitrate as N)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 5 samples exceed the criterion for Nitrate/Nitrite as N.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Maximum Contaminant Level for nitrate + nitrite (as N) that is incorporated by reference in the Water Quality Control Plan, Lahontan Region is 10.0 mg/L (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River, at Coleville]
Temporal Representation: | Data was collected over the time period 8/8/2007-12/26/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 31858 | Region 6
West Walker River

Pollutant: | Nitrite
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of five samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 31858, Nitrite | Region 6
West Walker River
LOE ID: | 44329
Pollutant: | Nitrite
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 5 samples exceed the criterion for Nitrite as N.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Water Quality Control Plan, Lahontan Basin, Objective for Municipal and Domestic Supply uses of inland surface waters states the following: waters shall not contain concentrations of inorganic chemicals in excess of the limits specified in California Code of Regulations, Title 22, Table 64431-A of section 64431 (Inorganic Chemicals). The maximum contaminant level listed in Table 64431-A for Nitrite as N is 1.0 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River, at Coleville]
Temporal Representation: | Data was collected over the time period 8/8/2007-12/26/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 21122 | Region 6
West Walker River

Pollutant: | Oxygen, Dissolved
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a one line(s) of evidence are necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Two of 16 samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used does not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. Two of 16 samples exceeded the objective and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 26 samples is needed for application of table 3.2. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 21122, Oxygen, Dissolved | Region 6
West Walker River
LOE ID: | 32271
Pollutant: | Oxygen, Dissolved
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 6
Number of Exceedances: | 2
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Two of 6 samples exceeded the water quality objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The objective from Lahontan Basin Plan Table 3-6, is a 1 day minimum dissolved oxygen concentration of 8.0 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data were collected at the following station: 631WWK001 - West Walker River, at Coleville.
Temporal Representation: | Samples were collected between August and December 2007
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 21122, Oxygen, Dissolved | Region 6
West Walker River
LOE ID: | 4927
Pollutant: | Oxygen, Dissolved
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Aquatic Life Use: | Fish Spawning
Number of Samples: | 10
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured dissolved oxygen under the Region 6 SWAMP program between 2002 and 2005. Ten samples had dissolved oxygen concentrations ranging from 8.3 to 11 mg/L. The objective was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | For waters designated for the COLD and SPWN beneficial uses the 1- day minimum objective is 8 mg/L (Lahontan Basin Plan Table 3-6)
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Ten samples were collected. One sample was collected in 2002 and the remainder were collected quarterly between 2003 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 30735 | Region 6
West Walker River

Pollutant: | PCBs (Polychlorinated biphenyls)
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30735, PCBs (Polychlorinated biphenyls) | Region 6
West Walker River
LOE ID: | 33260
Pollutant: | PCBs (Polychlorinated biphenyls)
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Zero of 1 sample collected for Total PCBs exceeded the evaluation guideline.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | Waters shall not contain substances in concentrations that result in deposition of material that causes nuisance or that adversely affects the water for beneficial uses (Lahontan Region Basin Plan).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for total PCB is 676 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data were collected at the following station 631WWK008 (West Walker River at Topaz).
Temporal Representation: | The samples were collected on 9/23/2008.
Environmental Conditions: |
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30736 | Region 6
West Walker River

Pollutant: | Permethrin, total
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30736, Permethrin, total | Region 6
West Walker River
LOE ID: | 44393
Pollutant: | Permethrin, total
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Permethrin, Total.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan for the Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The evaluation guideline for permethrin is the median lethal concentration (LC50) of 8.9 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 8.9 ug/g is the geometric mean of LC50 values for permethrin from Amweg et al. (2005).
Guideline Reference: | Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz - 631WWK008]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 32195 | Region 6
West Walker River

Pollutant: | Phosphorus
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. One of the samples exceed the water quality objective. For LOE ID # 4929, this data was not included in evaluation because there was a problem with holding times, adn so it should not be evaluated for listing purposes. LOE ID # 34532 was the only LOE evaluated in this decision. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of one samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 32195, Phosphorus | Region 6
West Walker River
LOE ID: | 4929
Pollutant: | Phosphorus
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 4
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled phosphorus under the Region 6 SWAMP program between 2002 and 2005. The total phosphorus concentration in 12 samples ranged from 0.022 to 1.41 mg/L. The highest value was from an August 2004 sample and probably reflects stormwater quality from a severe thunderstorm event. The annual average objective was exceeded in 4 of 4 years.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The site specific objective includes an annual average Total Phosphorus concentration of 0.01 mg/L and a 90th percentile value of 0.02 mg/L (Lahontan Basin Plan Table 3-15).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | 12 samples were collected between 2002 and 2005. Four annual average calculations were done.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Sampling and analysis were done according to the SWAMP QAPP. However, in July 2009 an error was discovered in the QAPP related to holding times for total phosphorus samples that affects the validity of data for the Lahontan Region The holding time for samples that are not acid-preserved.should be 48 hours rather than 28 days as indicated in the QAPP. "Low level" phosphorus analyses, without acid preservation, are used in the Lahontan Region's SWAMP program. .
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 32195, Phosphorus | Region 6
West Walker River
LOE ID: | 34532
Pollutant: | Phosphorus
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | The annual average for 2007 exceeds the water quality objective for Total Phosphorus. Total Phosphorus was calculated by summing Orthophosphate as P and Phosphorus as P data. Phosphorus as P data were averaged when they were collected on the same day. 4 pairs were summed and then averaged for 2007 before comparing with the Total Phosphorus annual average objective. The data was not used in cases where only Phosphorus as P was available without Orthophosphate.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | Table 3-15 of the Basin Plan states that the water quality objective for Total Phosphorus for West Walker River at Coleville is an annual average objective of 0.01 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected at West Walker River, at Coleville (631WWK001).
Temporal Representation: | Samples were collected on 8/8/2007, 9/18/2007, 11/8/2007, and 12/26/2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 31859 | Region 6
West Walker River

Pollutant: | Sodium Adsorption Ratio (SAR)
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. One of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of one samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 31859, Sodium Adsorption Ratio (SAR) | Region 6
West Walker River
LOE ID: | 32274
Pollutant: | Sodium Adsorption Ratio (SAR)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Agricultural Supply
Number of Samples: | 1
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | The annual average for year 2007 was 6.48 and does exceed the water quality objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The applicable site specific water quality objective from the amended Lahontan Basin Plan for the West Walker River states that the annual average SAR (sodium adsorption rate) should not exceed 2.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
| 2006. Amendments to the Water Quality Control Plan for the Lahontan Region: Revised Sodium-Related Standards for the Carson and Walker River Watersheds. Adopted October 12, 2006 under Resolution R6T-2006-0047
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data were collected at the following station: 631WWK001 - West Walker River at Coleville.
Temporal Representation: | Data was collected during August 2007 and November 2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 21002 | Region 6
West Walker River

Pollutant: | Specific Conductance
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 22 samples exceeded the criteria and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 21002, Specific Conductance | Region 6
West Walker River
LOE ID: | 4930
Pollutant: | Specific Conductance
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured specific conductance under the Region 6 SWAMP program between 2002 and 2005. Specific conductance in 12 quarterly field measurements ranged from 48 to 160 uS/cm. The MCL was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for specific conductance is 900 microsiemens per centimeter (uS/cm).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly field measurements were taken between 2002 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21002, Specific Conductance | Region 6
West Walker River
LOE ID: | 44380
Pollutant: | Specific Conductivity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 10
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 10 samples exceed the criterion for Conductivity(Us).
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Secondary MCL that is incorporated by reference in the Water Quality Control Plan, Lahontan Region for specific conductance is 900 uS/cm (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River, at Coleville]
Temporal Representation: | Data was collected over the time period 8/8/2007-12/26/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 21016 | Region 6
West Walker River

Pollutant: | Sulfates
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. For this decision, two different fractions were used (dissolved/total dissolved) although the same MCL objective was used for both 2010 and 2012 listing cycles. Therefore, these LOEs should be evaluated together to determine impairment. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 14 samples exceeded the criteria and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 21016, Sulfates | Region 6
West Walker River
LOE ID: | 4932
Pollutant: | Sulfates
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled sulfate under the Region 6 SWAMP program between 2002 and 2005. Sulfate concentrations in 12 quarterly samples ranged from 1.7 to 10.2 mg/L. The MCL was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for sulfate is 250 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly samples were collected between 2002 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21016, Sulfates | Region 6
West Walker River
LOE ID: | 32261
Pollutant: | Sulfates
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | The samples collected did not exceed the Water Quality Objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Secondary Maximum Contaminant Levels (SMCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The SMCL for Sulfates (SO4) is 250 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data were collected at the following station: 631WWK001 - West Walker River, at Coleville.
Temporal Representation: | Samples were collected on the following dates: 8/8/2007 and 11/8/2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 20766 | Region 6
West Walker River

Pollutant: | Temperature, water
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. One of the samples exceed the water quality objective. LOE ID # 4935 has a narrative objective whereas LOE ID # 44137 uses a numeric objective. Although this waterbody will not be listed, it may be difficult to evaluate it in the future since different objectives were used to determine impairment and we are uncertain of the ambient temperature or seasonality. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of 18 samples exceeded the guideline and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 20766, Temperature, water | Region 6
West Walker River
LOE ID: | 44137
Pollutant: | Temperature, water
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 6
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 1 of 6 samples exceed the criterion for Water Temperature.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Water Quality Control Plan for the Lahontan Region's water quality objective for all surface waters states the following: The natural receiving water temperature of all waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such an alteration in temperature does not adversely affect the water for beneficial uses. For waters designated COLD, the temperature shall not be altered.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).
Guideline Reference: | Fish introductions in CA: History and impact on native fishes. Davis, CA: University of CA, Davis
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River, at Coleville]
Temporal Representation: | Data was collected over the time period 8/8/2007-12/26/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 20766, Temperature, water | Region 6
West Walker River
LOE ID: | 4935
Pollutant: | Temperature, water
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured temperature quarterly under the Region 6 SWAMP program between 2002 and 2005. Twelve water temperature measurements ranged from 1.5 to 18.5 degrees Celsius. Sampling frequency was not sufficient to determine the natural temperature range or to detect whether changes have occurred.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The temperature objective in the Lahontan Basin Plan states: "The natural receiving water temperature of all waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such an alteration in temperature does not adversely affect the water for beneficial uses. For waters designated WARM, water temperature shall not be altered by more than five degrees Fahrenheit ... above or below the natural temperature. For waters designated COLD, the temperature shall not be altered. Temperature objectives for COLD interstate waters and WARM interstate waters are as specified in the 'Water Quality Control Plan for Control of Temperature in The Coastal and Interstate Waters and Enclosed Bays and Estuaries of California' including any revisions."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly temperature measurements were taken between 2002 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, and agricultural and highway drainage. Severe streambank erosion occurred during the January 1997 flood. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 32252 | Region 6
West Walker River

Pollutant: | Total Dissolved Solids
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Three of five samples exceed the objective COLD beneficial use; Zero of 12 samples exceed the criteria for MUN beneficial use of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Three of five samples exceeded the objective for COLD beneficial use; zero of 12 samples exceed the criteria for MUN beneficial use and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 32252, Total Dissolved Solids | Region 6
West Walker River
LOE ID: | 4934
Pollutant: | Total Dissolved Solids
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled TDS under the Region 6 SWAMP program between 2002 and 2005. TDS concentrations in 12 quarterly samples ranged from 27 to 109 mg/L. The MCL was not violated..
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for total dissolved solids (TDS) is 500 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly samples were collected between 2002 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 32252, Total Dissolved Solids | Region 6
West Walker River
LOE ID: | 32226
Pollutant: | Total Dissolved Solids
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | The annual average for TDS for this data set was 116.96 which exceeds the Water Quality Objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The site-pecific objective for Total Dissolved Solids (TDS) in Lahontan Basin Plan Table 3-15, includes an annual average of 60 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data were collected at the following station: 631WWK001 (West Walker RIver, at Coleville).
Temporal Representation: | Samples were collected between 8/8/2007 - 12/26/2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 32252, Total Dissolved Solids | Region 6
West Walker River
LOE ID: | 4933
Pollutant: | Total Dissolved Solids
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 2
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled TDS under the Region 6 SWAMP program between 2002 and 2005. TDS concentrations in 12 samples analyzed as "residue" ranged from 27 to 109 mg/L. The annual average objective was violated in 2 of 4 years. An additional sample analyzed as "nonfilterable" TDS was below the detection level.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The site-specific objective for total dissolved solids (TDS) iincludes an annual average of 60 mg/L and a 90th percentile value of 75 mg/L (Lahontan Basin Plan Table 3-15).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly samples analyzed as "residue" were collected between 2002 and 2005. Four annual average calculations were done. An additional single sample collected in May 2004 was analyzed as "nonfilterable."
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 22389 | Region 6
West Walker River

Pollutant: | Total Nitrogen as N
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Two of the samples exceed the water quality objective. LOE ID # 7778 had skewed samples due to samplign during high runoff and so may not be represenatitve of imparimetn of total Nitrogen as N. The new LOE ID 32326 showed no exceedences. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Two of five samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 22389, Total Nitrogen as N | Region 6
West Walker River
LOE ID: | 7778
Pollutant: | Total Nitrogen as N
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 2
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the West Walker River under the Region 6 SWAMP program between 2002 and 2005. Calculated total nitrogen values included three estimated values. Concentrations in the other 9 individual samples ranged 0.06 to 1.583 mg/L. These included two very high values that probably reflected high spring runoff and a summer thunderstorm event. Two of four annual averages included estimated values. The "average" for 2002 is a single estimated value. The average for 2003, counting the below detection level value as zero and disregarding the estimated value, was 0.033 mg/L. The averages for 2004 and 2005 were 0.532 and 0.438 mg/L. Both exceeded the objective but were skewed by the high single sample values.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The site-specific objective for total nitrogen (in Lahontan Basin Plan Table 3-15) includes an annual average of 0.20 mg/L and a 90th percentile value of 0.02 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly samples each (1 to 4 per year) were collected for total Kjeldahl nitrogen and nitrate plus nitrite between 2002 and 2005. Concentrations of total nitrogen were calculated from these samples. Four annual averages were calculated.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 22389, Total Nitrogen as N | Region 6
West Walker River
LOE ID: | 32326
Pollutant: | Total Nitrogen as N
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | The annual average did not exceeded the water quality objective for total nitrogen. Annual averages were calculated by water year starting in October 1st through September 30th. Total nitrogen was calculated by summing nitrate + nitrite as N data with TKN data when they were collected on the same day. Four pairs were summed and then averaged before comparing with the annual objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | Table 3-17 of the Basin Plan states that the water quality objective for nitrogen, total for West Walker River at Coleville is an annual average objective of 0.2 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected at West Walker River, at Coleville (631WWK001).
Temporal Representation: | Samples were collected on 8/8/2007, 9/18/2007, 11/8/2007, and 12/26/2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 30737 | Region 6
West Walker River

Pollutant: | Toxicity
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the criteria and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30737, Toxicity | Region 6
West Walker River
LOE ID: | 32014
Pollutant: | Toxicity
LOE Subgroup: | Toxicity
Matrix: | Sediment
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | One sample was collected to evaluate sediment toxicity. The sample did not exhibit significant toxicity. The toxicity test included survival and growth of Hyalella azteca. One sample can have multiple toxicity test results but will be counted only once. One sample is defined as being collected on the same day at the same location with the same lab sample id (if provided).
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life. Region 6 Basin Plan.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | Toxicity is defined as a statistically significant effect in the sample exposure compared to the control using EPA-recommended hypothesis testing. For SWAMP data exceedances are counted using the significant effect code: S equals significant, SG equals significantly greater and SL equals significantly lower. If a sample has any one of these codes, it will be considered an exceedance.
Guideline Reference: | Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates, Second Edition. U.S. Environmental Protection Agency Office of Research and Development, Duluth, MI , U.S. Environmental Protection Agency Office of Water, Washington, DC EPA-600/R-99/064
Spatial Representation: | The sample was collected at station 631WWK008.
Temporal Representation: | The sample was collected in September 2008.
Environmental Conditions: |
QAPP Information: | All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 30712 | Region 6
West Walker River

Pollutant: | Zinc
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of one samples exceeded the guidelines and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 30712, Zinc | Region 6
West Walker River
LOE ID: | 43865
Pollutant: | Zinc
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for West Walker River to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Zinc.
Data Reference: | Statewide Stream Pollution Trends Study 2008
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for zinc is 459 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: | Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
Spatial Representation: | Data for this line of evidence for West Walker River was collected at 1 monitoring site [ West Walker River at Topaz]
Temporal Representation: | Data was collected on a single day 9/23/2008.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan

DECISION ID | 22226 | Region 6
West Walker River

Pollutant: | pH
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. For the objective, it is based on ambient pH levels which are currently unknown, so this waterbody can not adequately be assessed for an impairment unless historical data exists to give a baseline for ambient pH levels. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 12 samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 22226, pH | Region 6
West Walker River
LOE ID: | 32258
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | There were 6 samples with pH ranging from 8 to 8.7. The normal ambient pH level for this water body is unknown and so it is unknown whether any exceedences occured.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The applicable objective states: "In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units." (Lahontan Basin Plan).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected at Station 631WWK001 - West Walker River, at Coleville.
Temporal Representation: | Samples were collected between 8/8/2007 and 12/26/2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 22226, pH | Region 6
West Walker River
LOE ID: | 4928
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured pH quarterly under the Region 6 SWAMP program between 2002 and 2005. 12 samples had field pH values ranging from 7.4 to 8.7 units.. (The 6.5 to 8.5 unit limits do not apply to waters designated for the COLD use.)
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The pH objective in the North Lahontan Basin Plan states: "In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly pH measurements were taken between 2002 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 28553 | Region 6
West Walker River

Pollutant: | Sedimentation/Siltation
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | Regional Board Conclusion: This pollutant was considered for placement on the section 303 (d) list in a previous listing cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: The West Walker River was delisted in 2006, based on State Water Board staff findings that the original listing basis was faulty due to lack of data and the fact that the original listing was in error (incorrect identification of water body). The actual issue was the failure of an irrigation diversion to Topaz Lake off the mainstem West Walker River, not the West Walker River itself. However, as a result of the 1997 flood, a significant segment of the irrigation diversion from the West Walker River to Topaz Lake (Topaz Lake diversion) was aggraded with sediment. This sediment has since been removed and the issue has been resolved. For the 2008 Integrated Report, Lahontan Water Board staff assessed suspended sediment data collected at a station on the river. The Lahontan Basin Plan's narrative water quality objective is an antidegradation based objective that provides that there shall be no increases in suspended sediment concentrations or loads. This pollutant is being considered for placement on the section 303(d) list under section 3.10 of the Listing Policy, which deals with trends in water quality. One line of evidence, based on quarterly sampling, is available in the administrative record to assess this pollutant. It includes 12 suspended sediment concentration values and 12 suspended sediment load values calculated from instantaneous discharge measurements. Suspended sediment concentrations and loads are dependent on flows and can change rapidly over a short time during storm or snowmelt runoff events. Quarterly samples are insufficient to capture these short term events and therefore are insufficient to define natural background suspended sediment concentrations and loads, or to detect trends. Listing Policy Section 3.10 requires that natural background conditions be established. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. Sampling frequency was insufficient to establish natural background conditions and therefore does not meet the requirements of Listing Policy section 3.10. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 28553, Sedimentation/Siltation | Region 6
West Walker River
LOE ID: | 4931
Pollutant: | Sediment
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the West Walker River under the Region 6 SWAMP program between 2002 and 2005. Suspended sediment concentrations in 12 samples ranged from 2 to 790 mg/L. Concurrent measurements of "instantaneous discharge" ranged from 25 to 1730 cubic feet per second. Calculated sediment loads ranged from 0.2 to 2090 tons/day. .
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's narrative objective for suspended sediment states: "The suspended sediment load and suspended sediment discharge rate of surface waters shall not be altered in such a manner as to cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly suspended sediment samples were collected between 2002 and 2005. Twelve load calculations were done.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, and agricultural and highway drainage. The watershed was affected by severe flooding in 1997 and wildfire in 2002. The headwaters are near the Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 28553, Sedimentation/Siltation | Region 6
West Walker River
LOE ID: | 2859
Pollutant: | Sedimentation/Siltation
LOE Subgroup: | Testimonial Evidence
Matrix: | Not Specified
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Assess Water Quality: | This listing was based on best professional judgment after staff observed turbid water in an irrigation channel that diverts water from the mainstem West Walker River into Topaz Lake. No data or other information was provided. The irrigation channel was mistakenly identified as the West Walker River, resulting in its listing (in error) for sedimentation as well. The West Walker River remained on the list following the extreme flood event of 1997, due to concerns over potential impacts from flooding. The original listing was in error (incorrect identification of water body). The actual issue was the failure of an irrigation diversion to Topaz Lake off the mainstem West Walker River, not the West Walker River itself. However, as a result of the 1997 flood, a significant segment of the irrigation diversion from the West Walker River to Topaz Lake (Topaz Lake diversion) was aggraded with sediment. The Walker River Irrigation District applied for and received permits and certifications to remove the sediment and restore the capacity of the diversion channel. The work was completed in late 2000 in accordance with the permit conditions. The sediment concerns in the Topaz Lake diversion have been resolved, and Regional Board staff is not aware of evidence to indicate current water quality standards exceedances or beneficial use impacts.
Data Reference: | Placeholder reference 2006 303(d)
SWAMP Data: | Non-SWAMP
Water Quality Objective/Criterion: |
Objective/Criterion Reference:
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: |
Temporal Representation: |
Environmental Conditions: |
QAPP Information: | QA Info Missing
QAPP Information Reference(s):

DECISION ID | 22297 | Region 6
West Walker River

Pollutant: | Total Kjeldahl Nitrogen (TKN)
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | Regional Board Conclusion: This pollutant was considered for placement on the section 303 (d) list in a previous listing cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. No biological data are available for assessment of compliance with the water quality objective for biostimulatory substances. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. There are no biological data available to assess whether the chemical samples exceeded the water quality objective. The data cannot be assessed using Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 22297, Total Kjeldahl Nitrogen (TKN) | Region 6
West Walker River
LOE ID: | 7776
Pollutant: | Total Kjeldahl Nitrogen (TKN)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled TKN under the Region 6 SWAMP program between 2002 and 2005. The TKN concentration in 12 samples ranged from 0.05 to 1.5 mg/L. The highest value was from an August 2004 sample and probably reflects stormwater quality from a severe thunderstorm event.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There is no site-specific objective for Total Kjeldahl Nitrogen (TKN) for the West Walker River. The Lahontan Basin Plan's objective for biostimulatory substances state : "Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Twelve quarterly samples were collected between 2002 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 22333 | Region 6
West Walker River

Pollutant: | Turbidity
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | Regional Board Conclusion: This pollutant was considered for placement on the section 303 (d) list in a previous listing cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under sections 3.2 and 3.10 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. Separate lines of evidence were prepared to assess data expressed as NTU and NTRU, since the two types of units reflect different optical properties and are not directly comparable. Four of 8 samples expressed as NTU exceed the California Maximum Contaminant Level (MCL) applicable under the water quality objective for Chemical Constituents. The MCL is expressed as NTU, and the four samples expressed as NTRU cannot be used to determine compliance with the MCL. The Lahontan Basin Plan's narrative objective for turbidity is antidegradation- based and allows no more than a 10 percent increase over natural turbidity levels. Listing Policy Section 3.10 provides direction for assessment of trends in water quality, including a requirement to document background conditions. Turbidity varies with streamflow and can change drastically over a single day depending on storm or snowmelt events. Continuous measurements of turbidity would be necessary to establish natural background conditions and detect trends of increased turbidity in violation of the objective. Quarterly samples are inadequate to determine compliance with the narrative objective under Listing Policy Section 3.10. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and turbidity values in streams of the Lahontan Region. 3. Four of 8 measurements expressed as NTU exceeded the MCL and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Sampling frequency was insufficient to define background conditions or detect changes (if changes occurred). Therefore there is insufficient information to assess compliance with the narrative turbidity objective under Listing Policy Section 3.10. 5. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 22333, Turbidity | Region 6
West Walker River
LOE ID: | 4937
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 8
Number of Exceedances: | 4
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured turbidity quarterly under the Region 6 SWAMP program between 2002 and 2004. Eight laboratory turbidity samples reported as NTU ranged from 2 to 500 units. The latter value, from a sample collected in August 2004, was probably the result of an intense summer thunderstorm. Of the eight samples reported as NTU, four exceeded the MCL.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for turbidity is 5 NTU.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Eight quarterly turbidity measurements reported as NTU were taken between 2002 and 2004.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 22333, Turbidity | Region 6
West Walker River
LOE ID: | 7750
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured turbidity quarterly under the Region 6 SWAMP program in 2004 and 2005. Two of four turbidity measurements reported as NTRU were below the detection level; the remaining two turbidity values were 2.6 and 54 NTRU.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The regionwide turbidity objective in the Lahontan Basin Plan states: "Waters shall be free of changes in turbidity that cause nuisance or adversely affect the water for beneficial uses. Increases in turbidity shall not exceed natural levels by more than 10 percent."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
| 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Four turbidity measurements reported as NTRU were taken quarterly in 2004 and 2005.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 22333, Turbidity | Region 6
West Walker River
LOE ID: | 7751
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured turbidity quarterly under the Region 6 SWAMP program in 2004 and 2005. Turbidity values in four samples reported as NTRU included two samples below the detection level, and two samples with values of 2.6 and 54 units.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no California or federal standards or criteria for turbidity expressed as NTRU. (The California Maximum Contaminant Level is 5 NTU.)
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Four quarterly turbidity measurements reported as NTRU were taken in 2004 and 2005..
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 22333, Turbidity | Region 6
West Walker River
LOE ID: | 4936
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 8
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured turbidity quarterly under the Region 6 SWAMP program between 2002 and 2004. Eight laboratory turbidity samples reported as NTU ranged from 2 to 500 units. The latter value, from a sample collected August 20, 2004, was probably the result of an intense summer thunderstorm. The next highest turbidity measurement was 17 NTU.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The regionwide turbidity objective in the Lahontan Basin Plan states: "Waters shall be free of changes in turbidity that cause nuisance or adversely affect the water for beneficial uses. Increases in turbidity shall not exceed natural levels by more than 10 percent."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, West Walker River near Coleville, was sampled.
Temporal Representation: | Eight quarterly turbidity measurements reported as NTU were collected between 2002 and 2004.
Environmental Conditions: | The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):